Pfizer and Allergan: The biggest Merger of all times

Pfizer is the pharma company which produces the high-selling drugs like and Lipitor. However, the company has been facing stiff competition from the generics drugs business. Infact, it is expected to cut Pfzier's sales by $28 billion from 2010 through next year.

Also read:

Buying Allergan would add its brand-name medicines for eye conditions, infections and heart disease to Pfizer's extensive portfolio of vaccines and drugs for cancer, pain, erectile dysfunction and other conditions. Botox maker Allergan is based in Ireland but runs much of its operations out of Parsippany, New Jersey.

If a deal is reached, it would be the biggest ever merger in health care and the largest "inversion" ever — that's a tax-saving maneuver in which a U.S. company reincorporates in a country with a lower corporate tax rate. Inversions have become a hot political topic, raising the ire of lawmakers in Washington and public interest groups.

According to the ctpost.com, terms of the deal include 11.3 Pfizer shares for every Allergan share, along with a small cash component. The boards of each company were expected to approve the agreement Sunday and it could be announced Monday.

Pfizer and Allergan representatives declined to comment.